The passage of time is relative depending on whether one is the stationary observer or the object/particle traveling at the speed of light (or close to it). I get this, kind of. But, when we talk about "it takes light X [units of time] to travel Y [units of distance]", where does time dilation come in? In the case of light's journey from the Sun to Earth, if we imagine the photons doing the actual speed-of-light travelling, is it 8 minutes for "them"? Or is it 8 minutes for us to observe their journey? Apologies in advance if it's a stupid question.
If I interpreted this article correctly, then the answer to my question should be: 8 minutes is what we perceive, whereas for the photon the journey is instantaneous, due to the fact that it travels AT the speed of light, not close to it, at which point "the photon itself experiences none of what we know as time: it simply is emitted and then instantaneously is absorbed, experiencing the entirety of its travels through space in literally no time. Given everything that we know, a photon never ages in any way at all."
When people talk about the time taken for light to go from the Sun to the Earth, they're generally just considering classical Newtonian mechanics, not relativity. So we simply divide the distance by the speed of light to get the time taken.
There are several other variables that affect this time, since the distance between the Earth and Sun is not constant (the orbit is an ellipse, and it's perturbed by other planets' (mostly Jupiter) gravity), and Earth is moving in its orbit. Unless you describe the time taken with extreme precision, all these effects, including time dilation, are negligible.
To measure the time light takes to travel, we run into an obstacle: if the observer is on Earth, they can not actually measure the point of time at which the photon is emitted from the Sun. Conversely, if the observer is the Sun (let's assume they have a magical spacesuit that protects them), they can measure the point of time at which the photon is emitted, but not the point of time at which it arrives on Earth.
To solve this, we might send one observer to the Sun, and one to Earth, give them synchronous clocks and have them both record the time at which the photon was sent and received. The problem with that is that 'synchronous clocks' is itself not well-defined if the clocks are at different locations. The best thing we can do, is give the two observers synchronous clocks while they are still on Earth, and then send one of them to the Sun, at a non-relativistic speed. After the measurement, this observer can return to Earth, and the observers can compare their observations. The recorded times between the emission and receiving of the photons will then be roughly 8 minutes (the relativistic corrections are small at this scale).
An easier way is to put a mirror on the sun and send a photon to it. The photon will return after 16 minutes.